DEVONIAN ROCKS OF CANADA WEST. 101 



8. Peof. McCot, British Palaosoic Fossils, p. 20. 



Pofessor McCoy tlius describes F. Gothlandica, — " Coralluin 

 forming irregularly pyriform or yery large circular, slightly convex 

 masses, with concentrically wrinkled base, composed of polygonal 

 tubes, averaging one line in diameter when adult, (but with occasional 

 large irregular spaces, in which the diameter is only half a line,) with 

 very numerous young smaller interpolated columns, of smaller diame- 

 ter, and fewer angles ; transverse diaphragms flat, about three in the 

 space of one diameter ; external walls as exposed in rough vertical 

 fracture, slightly roughened by small transverse wrinkles, which 

 obscurely crenulate the edges, sides with one or two rows of large 

 round communicating pores. 



** I agree with Mr. Lonsdale, in thinking that the Favosites 

 ahsaltica, (Goldf. Sp.) characterised by having but one row of pores 

 on each face of the tubes, should be viewed as only a variety of this 

 species ; as I think I have seen from one to three rows in portions of 

 a single mass. 



" Specimens from Q-erolstein, in the Eifel, seemed to agree (on 

 the most careful comparison of good specimens) perfectly with the 

 Silurian ones from "Wenlock, and the carboniferous ones from Derby- 

 shire. The great number of the young tubes gives a peculiar irregu- 

 larity of aspect to the surface of this species." 



It will be perceived by the above how widely the best palaeontolo- 

 gists differ in their descriptions of F. Gothlandica upon the same very 

 important point, the width of the corallites or tubes. According to 

 Professor McCoy, they are upon the whole less than one line in dia- 

 meter ; the adult cells, or the largest, only reaching that size, while 

 there are a great many much smaller. From Edwards and Haime we 

 learn that they are over one line, while by the figures of Goldfuss they 

 are shewn to be full one line and a half, the tubes above that size 

 being more numerous than those below. This diversity might not 

 appear to be of much consequence, and yet those geologists who have 

 had occasion to work a good deal among rocks abounding with these 

 corals know that the difference of half a line in the average size of the 

 tubes in two specimens of Favosites gives to them a very dissimilar 

 aspect, and strongly suggests the idea of two species. The more, 

 however, we examine into the subject the more evident does it become 

 that mere difference in size is not sufficient to separate species unless 

 the internal structure also differs. At all events the above comparison 



VOL. IV. I 



